Disk array apparatus and method for controllng the same

ABSTRACT

An apparatus includes a controller and a plurality of disk drives. The controller has a communication control unit for accepting a data input/output request, a disk controller unit for controlling a disk drive, and a cache memory for temporarily storing data transferred between the communication control unit and the disk controller unit. The plurality of disk drives has different communication interfaces and connected to the disk controller unit to communicate with the disk controller unit.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. Ser. No.12/370,846, filed Feb. 13, 2009, which is a continuation application ofU.S. Ser. No. 11/056,005, filed Feb. 14, 2006 (now U.S. Pat. No.7,523,258), which is a continuation of application Ser. No. 10/659,398,filed Sep. 11, 2003 (now U.S. Pat. No. 7,080,201), and which claimpriority to Japanese Patent Application No. 2003-145111, filed on May22, 2003, the contents of which all of which are incorporated herein byreference in their entirety. This application is related to U.S. Ser.No. 11/056,007, filed Feb. 14, 2005 (now U.S. Pat. No. 7,587,548), U.S.Ser. No. 11/056,006, filed Feb. 14, 2005 (now U.S. Pat. No. 7,461,203),U.S. Ser. No. 11/055,994, filed Feb. 14, 2005 (now abandoned), U.S. Ser.No. 11/056,002, filed Feb. 14, 2005 (now abandoned), U.S. Ser. No.11/056,001, filed Feb. 14, 2005 (now abandoned), and U.S. Ser. No.11/055,968, filed Feb. 14, 2005 (now abandoned), all of which arecontinuation applications of U.S. Ser. No. 10/659,398, filed Sep. 11,2003 (now U.S. Pat. No. 7,080,201) and the contents of all of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a disk array apparatus and a method forcontrolling the disk array apparatus.

DESCRIPTION OF THE RELATED ART

The quantity of data to be processed by a computer system has beenabruptly increased in these years. As a disk array apparatus formanaging such a large quantity of data, there has recently come topublic attention a large-scale disk array apparatus wherein a filesystem is coupled to a disk array apparatus of a RAID (Redundant Arraysof Inexpensive Disks) management type called mid-range class orenterprise class which offers a giant storage resource. For the purposeof efficiently using and managing such a giant amount of data, there hasbeen developed a technique by which the disk array apparatus and aninformation processor are connected by means of a dedicated network(Storage Area Network, which will be referred to as the SAN,hereinafter) to realize high-speed, large-amount access to the diskarray apparatus.

Meanwhile, in a related disk array apparatus, it has been common thatonly a disk drive having a specific type of communication interface isconnected to one disk controller unit. On the recent market, however,there are available various types of disk drives which are different intheir communication interface, access speed, etc., i.e., in Standard,price, etc. And from the viewpoint of the property, investment cost,etc. of a system to be operated, users' increasing need is to freelycombine such disk drives to form a disk array system having a flexiblearrangement. At the same time, another need is to utilize an existingdisk array system more effectively by minimizing a modification in thearrangement of the existing disk array system while allowing theaforementioned flexible combination.

SUMMARY OF THE INVENTION

In view of such circumstances, it is therefore a major object of thepresent invention to provide a disk array apparatus which can respond tothese needs, and also to provide a method for controlling such a diskarray apparatus.

In accordance with an aspect of the present invention, the above objectis attained by providing a disk array apparatus which includes acontroller and a plurality of disk drives. The controller has acommunication control unit for accepting a data input/output request, adisk controller unit for controlling a disk drive, and a cache memoryfor temporarily storing data transferred between the communicationcontrol unit and the disk controller unit. The plurality of disk driveshave different communication interfaces and are connected to the diskcontroller unit to communicate with the disk controller unit.

In this case, the disk controller unit has at least functions ofcontrolling the operations of the plurality of disk drives havingdifferent communication interfaces and monitoring the states or modes ofthe disk drives, which will be explained later. The communicationinterface is, for example, FC-AL (Fibre Channel Arbitrated Loop)interface, serial ATA interface, SCSI1 (Small Computer System Interface1) interface, SCSI2 (Small Computer System Interface 2) interface, SCSI3(Small Computer System Interface 3) interface, or ATA (AT Attachment)interface.

In this way, in the case of the disk array apparatus of the presentinvention, various types of disk drives having different communicationinterfaces, access speeds and storage capacities, i.e., differentStandards, prices, etc. can be combined with one disk controller unit,and thus an existing disk array apparatus can be effectively used whileminimizing a modification in the arrangement of the disk arrayapparatus.

Other objects and advantages of the present invention will become clearas the following description of the invention advances as detailed withreference to preferred embodiments of the invention as shown inaccompanying drawings.

In accordance with the present invention, there can be provided a diskarray apparatus wherein various types of disk drives different in theircommunication interface, access speed, etc., i.e., Standard, price, etc.can be freely combined with one disk controller unit, and thus anexisting disk array apparatus can be effectively used while minimizing amodification in the arrangement of the disk array apparatus, and alsocan be provided a method for controlling the disk array apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described inconjunction with the accompanying drawings, in which:

FIGS. 1A and 1B are front and back views showing an entire arrangementof a storage system in accordance with an embodiment of the presentinvention;

FIGS. 2A and 2B are exploded perspective views of a structure of amanagement terminal in the present embodiment;

FIGS. 3A and 3B show exploded perspective views of a physical diskmanagement table in the present embodiment;

FIG. 4 is a perspective view of an LU management table in the presentembodiment;

FIG. 5 shows an exemplary hardware arrangement of a disk array apparatusin the present embodiment;

FIG. 6 is a circuit diagram of the disk array apparatus in the presentembodiment;

FIG. 7 shows an example of a setting display screen in the presentembodiment;

FIG. 8 shows an example of a disk drive management table in the presentembodiment;

FIG. 9 shows an exemplary of a hardware arrangement of the presentembodiment used as an SES drive;

FIG. 10 shows a circuit configuration of an additional casing A 30 whichaccommodates only a SATA drive in the present embodiment;

FIG. 11 is a flow chart for explaining the exchanging operation of theSES drive in the present embodiment; and

FIG. 12 is a flow chart for explaining a processing sequence of controlof the operation of the disk drive and the cooling capability of acooling fan 66 in the present embodiment.

DESCRIPTION OF THE EMBODIMENTS

The present invention will be detailed in connection with embodiments ofthe invention with reference to the accompanying drawings.

1. Apparatus Arrangement

FIG. 1A is a front view of a disk array apparatus 10 to be explained inan embodiment of the present invention, FIG. 1B is a rear view of thedisk array apparatus 10, FIG. 2A is a perspective view when viewed fromthe front side of a basic casing 20 mounted in the disk array apparatus10, FIG. 2B is a perspective view when viewed from the rear side of thebasic casing 20, FIG. 3A is a perspective view when viewed from thefront side of an additional casing 30 to be mounted in the disk arrayapparatus 10, and FIG. 3B is a perspective view when viewed from theback side of the additional casing 30.

As shown in FIGS. 1A and 1B, the disk array apparatus 10 includes a rackframe 11 as its base. A plurality of stages of mount frames 12 areprovided inside of left- and right-side inner surfaces of the rack frame11 as arranged to be stacked in a vertical direction, each mount frameis formed in a back-and-front direction, and a basic casing 20 andadditional casings 30 are mounted along the mount frames 12 to be drawnor inserted therein in a drawer-like manner. As shown in FIGS. 2A and2B, boards and units for offering various types of functions to the diskarray apparatus 10 are mounted in the basic casing 20 and additionalcasing 30.

As shown in FIG. 2A, a plurality of disk drive units 52 each having adisk drive 51 provided therein are mounted as arranged in a row on thefront upper stage of the basic casing 20. In the present embodiment, thedisk array apparatus 10 includes a plurality of disk drives 51 havingdifferent communication interfaces. The disk drive 51 is, e.g., of atype having a communication interface having a communication functionbased on FC-AL Standard, SCSI1 (Small Computer System Interface 1)Standard, SCSI2 Standard, SCSI3 Standard, ATA (AT Attachment) Standard,or serial ATA (Serial ATA: SATA) Standard.

A battery unit 53, a display panel 54 for displaying the operating mode,etc of the disk drive 51, and a flexible disk drive 55 are mounted onthe front lower stage of the basic casing 20. A secondary battery isbuilt in the battery unit 53. The battery unit 53 functions as a backuppower source which supplies power to the board or unit when power supplyfrom an AC/DC power supply 57 is interrupted due to a power failure orthe like. Display devices including an LED indicator or lamp forindicating the operating mode of the disk drive 51 are provided on thedisplay panel 54. The flexible disk drive 55 is used as when amaintenance program is loaded.

As shown in FIG. 2B, one power controller board 56 is mounted on each ofboth sides of the upper stage of the back side of the basic casing 20.The power controller board 56 is connected to communicate with theplurality of disk drives 51. The power controller board 56 and theplurality of disk drives 51 are connected by a loop communication linesuch as, e.g., a communication line based on the FC-AL scheme (topology)to communicate with each other.

Mounted on the power controller board 56 are a PBC (Port Bypass Circuit)160 for controlling an FC-AL 150 formed between the disk drives 51 aswell as a circuit for monitoring the states of the AC/DC power supply 57and disk drives 51, for controlling power supply of the disk drives 51,for controlling the cooling capability of a cooling device, forcontrolling display devices on the display panel 54, and for monitoringthe temperature of each casing. In this connection, the cooling deviceis a device for cooling the interior of the disk array apparatus 10 andthe interiors of the casings 20 and 30, such as, e.g., an intercooler, aheat sink or an air-cooling type cooling fan.

A connector 67 for a fiber channel cable is provided to the powercontroller board 56, and a fiber channel cable 91 forming part of theline of the FC-AL 150 is connected to the connector 67. In thisconnection, the details of the FC-AL 150 is incorporated, for example,in JP-A-2001-167040 (corresponding to U.S. patent application Ser. No.09/608,151), JP-A-2001-337868, or JP-A-2001-222385 (corresponding toU.S. patent application Ser. No. 09/758,684 published as U.S. PatentApplication Publication US2001/0014956A1).

As shown in FIG. 2B, two of the AC/DC power supplies 57 are mounted sideby side in a space defined by two of the power controller boards 56 onthe back sides of the upper stage of the basic casing 20. The AC/DCpower supplies 57 supply power to the disk drives 51, boards, unit, etc.The AC/DC power supplies 57 are connected to the power controller boards56 to supply power to the respective disk drives 51 according to signalsfrom the power controller boards 56.

For the purpose of getting security of the power supply of therespective casings 20 and 30, in the present embodiment, two of thepower controller boards 56 and two of the AC/DC power supplies 57 havebeen redundantly mounted in the basic casing 20 and additional casing 30respectively. However, each power controller board 56 and each AC/DCpower supply 57 may be mounted to each of the casings.

A breaker switch 64 for turning ON and OFF the output of the AC/DC powersupply 57 is provided to the AC/DC power supply 57.

As shown in FIG. 2B, two wind-assisted cooling fan units 58 are mountedside by side as located under the AC/DC power supplies 57 respectively.One or more cooling fans 66 are mounted in the wind-assisted cooling fanunit 58. The cooling fan 66 acts to supply air into the casing ordischarge air therefrom to expel heat generated in the disk drives 51 orAC/DC power supply 57. In this case, the basic casing 20 and additionalcasing 30, and the boards and units mounted thereto are designed to beformed therein with ventilating passages or ports for circulation of airwithin the casings 20 and 30, enabling efficient discharging of heatwithin the casing 20 to the outside thereof by the cooling fans 66.Although the cooling fan 66 can be provided for each of the disk drives51, it is preferable to provide a large cooling fan 66 for each casingbecause the necessary number of chips or units can be reduced.

The wind-assisted cooling fan unit 58 is connected to a control board 59or wind-assisted cooling fan unit 58 by a control line 48 so that thecontrol board 59 or power controller board 56 controls the rotationalspeed of the cooling fan 66 of the wind-assisted cooling fan unit 58through the control line 48.

As shown in FIG. 2B, a single piece of control board 59 is mounted ontothe lower stage of the back side of the basic casing 20. Mounted on thecontrol board 59 are a communication interface with the disk drives 51mounted in the basic casing 20 and additional casing 30, a circuit forcontrolling the operations of the disk drives 51 (e.g., based on a RAIDscheme) or for monitoring the modes of the disk drives 51, and so on.

In the present embodiment, though the power controller board 56 isprovided to control the power supply to the disk drives 51 and thecooling capability of the cooling device, such control may be carriedout by the control board 59.

In the present embodiment, further, an interface board 61 having acommunication interface function with a host computer 300 based on,e.g., the SCSI Standard or fiber channel Standard, a cache memory 62 forstoring therein data to be written or read out to or from the diskdrives 51, and so on are mounted on the control board 59. However, theseelements may be mounted to another board.

Mounted to the interface board 61 mounted on the control board 59 is anexternal connector 63 which is based on a predetermined interfaceStandard of a fiber channel, a SAN (Storage Area Network) or LAN (LocalArea Network) according to the protocol such as Ethernet (registeredtrademark), or SCSI for connection with the host computer 300. The hostcomputer 300 is connected to the interface board 61 at the externalconnector 63 connected to a communication cable 92.

In this connection, for the purpose of getting security of control ofthe disk drives 51 of the basic casing 20, two of the control boards 59may be redundantly mounted.

As shown in FIG. 3A, a plurality of disk drive units 52 having diskdrives 51 accommodated therein are mounted in a row in the front side ofthe additional casing 30. As shown in FIG. 3B, the single powercontroller board 56 is mounted on each of right and left sides of theback of the additional casing 30. Also provided in a space defined bythe two power controller boards 56 are two of the AC/DC power supplies57 side by side. Two of the cooling fan units 58 are mounted under theAC/DC power supplies 57 side by side. The breaker switch 64 for turningON or OFF the output of the associated AC/DC power supply 57 is providedto the associated AC/DC power supply 57.

As has been explained above, in the present embodiment, for the purposeof getting security of the power supply of the additional casing 30, thetwo power controller board 56 and the two AC/DC power supplies 57 areredundantly mounted in the additional casing 30 side by side each two.However, the single power controller board 56 and the single AC/DC powersupply 57 can be mounted in the additional casing. Further, thefunctions of the power controller board 56 including the control of thepower supply to the disk drives 51 and the control of the coolingcapability of the cooling device may be provided to the control board59.

FIG. 4 shows an example of the structure of the disk drive 51accommodated in the disk drive unit 52. The disk drive 51 includes acasing 70, a magnetic disk 73, an actuator 71, a spindle motor 72, ahead 74 for reading or writing data, a mechanism control circuit 75 forcontrolling the mechanical part of the head 74, etc., a signalprocessing circuit 76 for controlling a data read/write signal to themagnetic disk 73, a communication interface circuit 77, an interfaceconnector 79 through which various commands or data are input or output,a power connector 80, all accommodated in the casing 70.

The disk drive 51 is, for example, a 3.5-inch-sized magnetic disk of acontact start/stop (CSS) type or a 2.5-inch-sized magnetic disk of aload/unload type. The 3.5-inch magnetic disk has a communicationinterface based on, e.g., SCSI1, SCSI2, SCSI3 or FC-AL. The 2.5-inchmagnetic disk, on the other hand, has a communication interface basedon, e.g., serial ATA or ATA.

When the 2.5-inch magnetic disk is accommodated in the casing 20 or 30of the disk array apparatus 10, it may be accommodated in a containerhaving a 3.5 inch shape. With it, the shock resistance performance ofthe magnetic disk can be increased. In this connection, the 2.5- and3.5-inch magnetic disks are different not only in their communicationinterface but also in the I/O performance, power consumption, life, etc.When compared with the 3.5-inch magnetic disk, the 2.5-inch magneticdisk has a bad I/O performance and a short life. When compared with the3.5-inch magnetic disk, however, the 2.5-inch magnetic disk is superiorthereto in that it has less power consumption.

2. Hardware Arrangement of Disk Array Apparatus

FIG. 5 is a block diagram of a hardware arrangement of the disk arrayapparatus 10 for explaining it as an embodiment of the presentinvention.

As shown in FIG. 5, the disk array apparatus 10 is connected with thehost computer 300 via a SAN 200, and also connected with a managementcomputer 500 via a LAN 400. The host computer 300 is an apparatus whichaccesses the disk array apparatus 10, such as a personal computer, awork station or a mainframe computer. The management computer 500, whichis a computer for operating and managing the disk array apparatus 10, isconnected to the disk array apparatus 10 via the LAN (Local AreaNetwork) 400. The LAN 400 is a network which is connected between thedisk array apparatus 10 and management computer 500 to performcommunicating operation based on a protocol such as, e.g., TCP/IP. Inthis connection, it is not necessarily required that the managementcomputer 500 be connected by a communication means such as the LAN 400,but the management computer 500 may be connected by means of acommunication line or bus line based on the SCSI (Small Computer SystemInterface) Standard or in a peer-to-peer relationship.

The disk array apparatus 10, which is managed, e.g., by a system center,data center or the like in a company or corporation, functions as anapparatus for previously storing data to be processed by the hostcomputer 300. The host computer 300 in turn is a computer which offerssuch a service as, e.g., an automatic deposit/payment service in a bankor a homepage browsing service in the Internet.

The disk array apparatus 10 and host computer 300 are connected by theSAN 200. The SAN 200 is a network which is connected between the diskarray apparatus 10 and host computer 300 to communicate with each otheraccording to, e.g., a fiber channel protocol.

<Disk Array Apparatus>

The disk array apparatus 10 is a computer having a CPU (CentralProcessing Unit) and a memory. When various programs are executed undercontrol of the CPU of the disk array apparatus 10, various functions canbe implemented. The disk array apparatus 10 performs control over diskdrives 51α and 51β according to a command received from the hostcomputer 300. For example, when receiving an input/output request ofdata sent from the host computer 300, the apparatus perform performsdata input/output operation over the disk drives 51α and 51β. The datais stored in a logical volume as a storage area logically set onphysical storage areas provided by the disk drives 51α and 51β of thedisk array apparatus 10. The disk array apparatus 10 also sends orreceives various commands to and from the host computer 300 to managethe disk array apparatus 10.

The disk array apparatus 10 includes the basic casing 20 and one or moreof the additional casings 30, as has already been explained. In thepresent embodiment, the basic casing 20 has a controller 100, diskdrives 51α, an FC-AL 150, port bypass switches 160, and terminals 180.The controller 100 has a communication control unit 110, a diskcontroller unit 120, a cache memory 62, and a bus 140. The controller100 is mounted on the above control board 59. The additional casing 30has disk drives 51β, an FC-AL 150, port bypass switches 160, converters170 and terminals 180.

The communication control unit 110 has an interface for communicationwith the host computer 300. The interface of the communication controlunit 110 is, for example, a host bus adaptor (HBA) which connects thedisk array apparatus 10 to the SAN 200. As a result, the disk arrayapparatus 10 can transmit or receive various data input/output commandsor data to or from the host computer 300. The interface of thecommunication control unit 110 is such a communication interface board61 as mentioned above.

The bus 140 is wired between the communication control unit 110, diskcontroller unit 120 and cache memory 62 to mutually connect these. Datatransfer between the communication control unit 110, disk controllerunit 120 and cache memory 62 is carried out via the bus 140.

The cache memory 62 is a memory element to be used by the communicationcontrol unit 110 and disk controller unit 120. The cache memory 62 isused to temporarily store data transferred between the communicationcontrol unit 110 and disk controller unit 120. Since the communicationcontrol unit 110 or disk controller unit 120 uses the cache memory 62,the data writing or reading operation can be efficiently carried out.

The terminal 180 provided to the basic casing 20 or additional casing 30is a metal fitting which connects together a connection line in thebasic casing 20 and a connection line in the additional casing 30. Dataor command transfer between the disk controller unit 120 of the basiccasing 20 and the disk drive 51β accommodated in the additional casing30 is carried out via the terminals 180.

The disk controller unit 120 executes operations of writing or readingout data in or from the disk drives 51α and 51β in response to a datainput/output request from the communication control unit 110. The diskcontroller unit 120 writes data read out from the disk drives 51α and51β in the cache memory 62. Further, the disk controller unit 120acquires data written in the cache memory 62 by the communicationcontrol unit 110 and writes it in the disk drives 51α and 51β.

The disk controller unit 120 may have such a function as to control thedisk drives 51α and 51β at a so-called RAID (Redundant Array ofInexpensive Disks) level (e.g., 0, 1, 5) prescribed in the so-calledRAID system.

Further, the disk controller unit 120 may perform management control ofa copy of data stored in the disk drives 51α and 51β or backup controlthereof.

In addition, for the purpose of preventing data disappearance or lossdue to occurrence of a disaster (disaster recovery), the disk controllerunit 120 may have a function (data replication function (remote copy))of storing a copy of data of the disk array apparatus 10 at a primarysite also in another disk array apparatus installed at a secondary site.

The FC-AL 150, which is one of fiber channel systems (topologies), actsto connect the disk controller unit 120 and disk drives 51α and 51β by aloop-like connection line (transmission line) to communicate with eachother. In this connection, the disk controller unit 120 and disk drives51α and 51β may be communicably connected with each other by means of anFC-AL hub or directly by a connection line such as a fiber channelcable.

The FC-AL 150 has a plurality of port bypass switches (PBC's) 160. ThePBC 160 has a main function of connecting the disk controller unit 120and a plurality of disk drives 51α and 51β by the FC-AL 150. The PBC160, which is an electronic switch in the form of a chip, also has afunction of bypassing the disk controller unit 120 and disk drives 51αand 51β to electrically remove the disk controller unit and disk drives51α and 51β from the FC-AL 150. More specifically, the PBC 160 separatesthe disk drive 51, which became faulty, from the FC-AL 150 thus enablingcommunication between another disk drive 51 and disk controller unit120.

The PBC 160 also enables insertion and removal of the disk drive 51 withsuch a condition that the operation of the FC-AL 150 remains. Forexample, when the disk drive 51 is newly mounted, the disk drive 51 isincorporated into the FC-AL 150 to enable communication with the diskcontroller unit 120. In this connection, the circuit board of the PBC's160 may be provided to the rack frame 11 of the disk array apparatus 10,or all or some of the PBC's may be mounted to the control board 59 orpower controller board 56.

Accommodated in the disk array apparatus 10 are the plurality of diskdrives 51α and 51β having different communication interfaces (differentcommunication Standards) for communication with the disk controller unit120. The communication Standards of the communication interfacespossessed by the disk drives 51α and 51β include, for example, fiberchannel (FC), SCSI1 (Small Computer System Interface 1), SCSI2, SCSI3,ATA (AT Attachment) and Serial ATA (SATA). In the present embodiment,the disk drives 51α have a fiber channel interface and the disk drives51β have an SATA interface. However, the present invention is notlimited to the specific example.

The converter 170 is a device which converts data or signal to make thecommunication interface not adapted to the communication scheme of thecommunication line with the disk controller unit 120 confirm to theaforementioned communication scheme. The converter 170 is, for example,an SCSI-ATA (IDE: Integrated Device Electronics) converter, an FC-SATAconverter, or an ATA (IDE)-SATA converter. When the disk drive 51β isconnected to the FC-AL via the converter 170, the disk drive 51β cancommunicate with the disk controller unit 120. The converter 170 mayalso be provided in such a form as to be built in the disk drive 51β, ormay also be provided in such a form as to be installed outside of thedisk drive 51β.

<Management Computer>

The management computer 500 is a computer for maintaining and managingthe disk array apparatus 10 connected thereto by the LAN 400. Themanagement computer 500 is, for example, a personal computer, aworkstation, a mainframe computer or the like.

The management computer 500 has a CPU, a memory and so on, and the CPUof the management computer 500 performs general control over themanagement computer 500 in such a manner that the computer realizesvarious functions by executing various programs stored in the memory.

When the operator operates the management computer 500, for example, hecan set the arrangements of the disk drives 51α and 51β, manage or setlogical volumes (capacity management, capacity extension or reduction,assignment of the host computer 300, etc.), and so on. As an example ofsetting the arrangements of the disk drives, addition or reduction ofthe number of disk drives 51α and 51β or modification of the RAIDconfiguration (e.g., modification from RAID1 to RAID5) can be carriedout. Further, the confirmation of the operating mode of the disk arrayapparatus 10 or the identification of a fault location can also be done.These settings are realized by the operator who uses the Web pageoffered by the Web server operated by the management computer 500 as auser interface. The management computer 500 may also be provided in sucha form as to be built in the disk array apparatus 10 or in such a formas to be installed outside thereof.

The management computer 500 may be used as a computer for exclusivemaintenance and management of the disk array apparatus 10 and diskdrives 51α and 51β, or such maintenance/management functions may beprovided to a general purpose computer.

From the above reasons, in the case of the disk array apparatus 10 ofthe present invention, various types of disk drives different incommunication interface, access speed, storage capacity and price can befreely combined with the single disk controller unit, and modificationin the arrangement of an existing disk array apparatus can be minimizedand thus the existing apparatus can be effectively used.

3. Circuit Configuration

In such a condition that the basic casing 20 and additional casing 30are mounted in the rack frame 11, the boards and units mounted in thesecasings 20 and 30 are wired by internal wiring lines or circuits (notshown) provided to the rack frame 11 or by external wiring lines tothereby establish such a circuit as shown in FIG. 6. In this drawing,thick lines indicate the FC-AL's 150, thin lines indicate the controllines 48, and dashed lines indicate power supply lines 49, respectively.Provided on the FC-AL's 150 are terminals (e.g., connectors) 190 forconnection with the disk drives 51α and 51β and the boards and units ofthe disk controller unit 120. The disk controller unit 120 is providedin the form of a circuit including a CPU, a protocol control chip,memories such as RAM and ROM and mounted on the control board 59; andfunctions to control and monitor the disk drives 51α and 51β mounted inthe basic casing 20 and additional casings A and B (30).

A main switch 85 is provided, e.g., on the front side of the basiccasing 20, so that, when the control board 59 is mounted to the basiccasing 20 for example, an output signal line 87 of the main switch 85 isconnected to the disk controller unit 120. In this connection, the mainswitch 85 may also be provided to the rack frame 11, in which case, thebasic casing 20 is mounted to the rack frame 11. For this reason, theoutput signal line 87 can also be connected to the disk controller unit120.

A power controller 81 is mounted on the power controller board 56. Thepower controller 81 has memories such as CPU, RAM and ROM and also hasvarious types of control chips. The power controller 81 has wiring linesconnected to the wind-assisted cooling fan unit 58 and AC/DC powersupply 57. The power controller 81 controls and monitors such boards andunits mounted in the basic casing 20 and additional casings A and B (30)as the wind-assisted cooling fan unit 58, AC/DC power supply 57 and diskdrives 51α and 51β.

The power controller 81 for each of the casings 20 and 30 is connecteddirectly to the disk controller unit 120 via the control line 48. Thepower controller 81 may also be connected to the disk controller unit120 via an SES drive to be explained later.

The power controller 81, in response to a power supply signal or powercut-off signal of the disk drives 51α and 51β received from the diskcontroller unit 120, transmits to the AC/DC power supply 5 a signalindicative of power supply to the respective disk drives 51α and 51β ora signal indicative of power cut-off to the disk drives 51α and 51β. Asa result, the AC/DC power supply 57 can supply power to the disk drives51α and 51β or can stop power supply thereto.

At the same time, according to the operating modes of the disk drives51α and 51β accommodated in the casings, the power controller 81controls the rotational speed of the cooling fan 66. In this connection,the control of the rotational speed of the cooling fan 66 may be carriedout in units of each of the disk drives 51α and 51β or in units of eachcasing. The control of the rotational speed of the cooling fan enablesreduction of power consumption of the apparatus. Further, since therotational speed of the cooling fan is controlled depending on theoperating modes of the disk drives 51α and 51β, the present disk arrayapparatus can realize noise prevention more effectively than a diskarray apparatus not for controlling the rotational speed.

4. Operation <Operating Mode of Disk Drive>

The disk drive 51, when receiving a command from the disk controllerunit 120, is switched to any one of operating modes of “ready”, “notready” and “power off”. The disk drive 51 operating in the “ready” modecan accept read/write command of data sent from the disk controller unit120. The disk 73 of the disk drive 51 operating in the “ready” mode isrotating with a rotational speed necessary for data reading/writing(spin up state). The average power consumption of the disk drive 51becomes maximum when the disk drive is operating in the “ready” of theabove three modes.

When the disk drive 51 is operating in the “not ready” mode, the diskdrive 51 is not rotating with a rotational speed necessary for the datareading/wring (spin down state). The disk drive 51 operating in the “notready” mode cannot accept a command relating to the datareading/writing, but can accept a specific type of command such as,e.g., a command indicative of shift to the “ready” mode. The averagepower consumption of the disk drive 51 operating in the “not ready” modeis less than that in the “ready” mode.

When the disk drive 51 is in the “power off” mode, the disk drive 51cannot accept a command sent from the disk controller unit 120. Further,the rotation of the disk 73 of the disk drive 51 is completely stopped.The average power consumption of the disk drive 51 is zero in the “poweroff” mode.

The aforementioned operating mode of the disk drive 51 can be changed,for example, by an operator who operates a setting display screenpresented by a software program run by the management computer 500. Anexample of such setting screen is shown in FIG. 7. Since the operatingmode of each of the disk drives 51 can be controlled on the settingscreen, the operation and management of the apparatus can be improved.

The scheme of the communication interface of the disk drive 51 in FIG. 7can be acquired by the following method. That is, when the diskcontroller unit 120 inquires the disk drive 51 accommodated in the basiccasing 20 and additional casing 30 via the FC-AL 150 (e.g., by polling),the disk controller unit can know the scheme (standard) of thecommunication interface of the each disk drive 51. For example, when acommand is sent to the each disk drive 51, the type of the communicationinterface scheme is set to be informed from the disk drive 51. The diskcontroller unit 120 stores the type of the communication interfaceStandard informed from the disk drive 51 in a disk drive managementtable as associated with the corresponding disk drive 51. The disk drivemanagement table is stored, for example, in the memory or the disk drive51. FIG. 8 shows an example of the disk drive management table. Recordedin the disk drive management table are identifiers of the disk drives 51accommodated in each casing, communication interface schemes of the diskdrives 51, and operating modes of the disk drives 51. In thisconnection, the above inquiry may be carried out when the disk arrayapparatus 10 is operated or when the user mounts the disk drive 51 inthe casing 20 or 30.

With it, the disk controller unit 120 can control the operating mode ofeach disk drive. Further, the disk controller unit 120 can also controlsuch operating mode in units of a group of disk drives or in units ofcasing. As a result, the disk drives can be grouped according to theirusage purpose to form groups of drives or a casing for exclusive backupor fix contents which can temporarily save power. For example, suchdrives having a short life as SATA drives can be used as drivesexclusively for backup or fix contents, such drives can be collectivelycontrolled so that the drives are put in the “power off” mode when notused or are operated in the “ready” mode as necessary. As a result, notonly the use power can be reduced but also the life of the drives can beunified and the average life of the drives can be secured, thusincreasing its maintenance efficiency. Furthermore, since the operatingmodes of the disk drives can be controlled in units of disk drive group,the operation and management of the apparatus can also be improved.

<SES Drive>

Shown in FIG. 9 is an example when the disk drives 1 to 4 (51α) of theadditional casing A 30 are used as SES drives. In the presentembodiment, it is assumed that the power controller 81 and diskcontroller unit 120 are connected by the SES drives. The word “SES (SCSIEnclosure Services) drive” refers to such a disk drive 51 that causesthe disk controller unit 120 and the power controller 81 for control ofthe power supply of the disk drive 51 to be connected to each othercommunicably with each other.

The SES drive has an SES (SCSI Enclosure Services) or ESI (EnclosureService I/F) prescribed in SCSI3 (Small Computer System Interface 3)Standard. And the SES or ESI function can be activated by connectingpredetermined signal pins of the interface connector 79.

In the present embodiment, the disk drives 1 to 4 (51α) of theadditional casing A 30, i.e., FC drives are employed as SES drives asshown in FIG. 9, but the disk drives 51 having another communicationinterface may be used as the SES drives. Further, one or a plurality ofdisk drives 51 may be used as SES drives. In the present embodiment, thedisk drives 5 to 8 (51β) of the additional casing A 30 as shown in FIG.9 are of a SATA type.

In this way, since the SES function is provided to the specific diskdrive(s) 51, the need for provision of the control line 48 forconnection between the disk controller unit 120 and power controller 81can be eliminated. Further, The disk controller unit 120 can control theoperating mode of another disk drive via the SES drive.

When the SES drives are fixed to certain specific disk drives 51 asmentioned above, the life of the disk drives 51 can be shortenedremarkably. To avoid this, it is considered to operate as rotationallyshifted the disk drives 51 functioning as the SES drives. By operatingthe disk drives 51 as rotationally shifted in this way, the life of theSES drives can be prolonged. Explanation will next be made as to therotational shift use of the SES drives.

<Rotational Shift of SES Drives>

Explanation will be made as to a mechanism wherein SES drives in theadditional casing A 30 having the SATA drives alone housed therein areshifted by rotation under control of a software program, by referring toFIG. 10. The drawing shows a circuit configuration of the additionalcasing A 30 having the SATA disk drives (disk drive A to F) (51β) housedtherein.

A signal for control of power or the like is applied to a terminal 1(190) from the basic casing 20 via the FC-AL 150. The signal arrives atthe power controller 81 via a terminal 3 (190), SES drive (SATA drive A)51β and control line 48. At this time, since the SATA drive A (51β) isoperating in the “ready” or “not ready” mode, the signal for control ofpower or the like can arrive at the power controller 81 via the diskdrive A (51β).

The power controller 81, when receiving the power control signal fromthe basic casing 20, controls the power supply to the power fan, therotational speed of the fan, etc. In this case, it is assumed that poweris already supplied to the SATA drive A (51β), power controller 81 andcooling fan 66 in an initial state. Further the cooling fan 66 isoperating in a low-power-consumption mode.

When receiving a signal from the basic casing 20 to the additionalcasing 30 to put the respective disk drives 51β in the “ready” mode, thepower controller 81 changes the rotational speed of the cooling fan 66to a value in its normal operation and controls switches SW2 to SW6(195) to start power supply to the SATA drives B-F (51β).

Explanation will next be made as to how the power controller 81 changesthe SES drive from the SATA drive A (51β) to the SATA drive B (51β).FIG. 11 shows an example of a SES drive changing procedure. As shown inFIG. 11, when receiving a signal from the basic casing 20 to change theSES drive to another disk drive 51β and to put the latter drive in the“power off” mode (S1100), the power controller 81 controls the switchesSW1 and SW3 to SW6 (195) to stop power supply to the SATA drive A (51β)and to the SATA drives C-F (51β) (S1101). Thereafter, the operation ofthe SATA drive B is controlled to be in the “not ready” mode (S1102) andthe rotational speed of the cooling fan 66 is operated in thelow-power-consumption mode (S1103), whereby the additional casing 30 isput in the “power off” mode (low-power-consumption operational mode).Next, when a signal for control of power or the like comes from thebasic casing 20, the signal is transmitted to the power controller 81via the SATA drive B (51β).

In this connection, the apparatus is designed so that, in response tooperator's instruction, the signal indicative of the change of the SESdrive to be received by the power controller 81 can be transmitted tothe power controller 81 from the basic casing 20, but the signal canalso be transmitted from the basic casing 20 at the timing set by theuser.

As mentioned above, when the power controller 81 receives the signalindicative of change of the SES drive from the basic casing 20, the SESdrive is changed from the SATA drive A (51β) to the SATA drive B (51β).As the SES drive changing operation is carried out sequentially from theSATA drive A (51β) to another SATA drive (51β), the SES drive issequentially changed. Since the SES drive is sequentially changed inthis way, the lives of the disk drives 51β can be made equal to eachother. However, the method of shifting the SES drive by rotation is notlimited to the above specific method, but another method can beconsidered readily by those skilled in the art in the form of a circuitconfiguration or the like.

<Basic Operation of Disk Array Apparatus>

Since the disk controller unit 120 communicates with the disk drive 51housed in the basic casing 20 and additional casing A 30 via the FC-AL150, the disk controller unit 120 can know whether disk drive 51 is inany of the modes “ready”, “not ready” and “power off”. Further, the diskcontroller unit 120 transmits a command to the disk drive 51 to controlthe operation of the disk drive 51. In this connection, thecommunication for the mode grasp and control is carried out according toa protocol such as FC-AL or FCP (Fiber Channel Protocol for SCSI). Thedisk controller unit 120 also controls the cooling ability of thecooling fan 66 according to the operational mode of the disk drive unit52.

Such control is carried out, for example, when the user wants to changethe operational mode of a specific disk drive 51 on such a settingdisplay screen as shown in FIG. 7 or when a data write/read request isissued from the host computer 300 to the disk drive 51 in the “poweroff” mode. Such control is also carried out even when data stored in thedisk drive 51 (put in the “ready” mode) is to be stored in the diskdrive 51 (in the “power off” mode) for exclusive backup in response touser's instruction or the like. Explanation will be made below inconnection with an example of a processing sequence wherein, in responseto users backup instruction or the like, how the operation of the diskdrive 51 and the cooling ability of the cooling device are controlled.

FIG. 12 shows a flow chart for explaining a processing sequence tocontrol the operation of the disk drive and the cooling ability of thecooling fan 66.

The management computer 500 first transmits a backup request to the diskarray apparatus 10 via the LAN 400 for backup. The disk array apparatus10, when receiving the backup request, refers to the disk drivemanagement table stored in the memory or disk drive 51, confirms theoperational mode of the disk drive 51β as a backup destination, andstarts its backup operation. In this case, it is assumed in its initialstate that the disk drive 51β housed in the additional casing A 30 isput in the “power off” mode and the cooling fan 66 is operating in the“low-power-consumption” mode. It is also assumed that the disk drive 51αhoused in the basic casing 20 is put in the “ready” mode and the coolingfan 66 is operated in the normal mode.

When the disk array apparatus 10 receives the backup request (S1200),the apparatus transmits a command to the power controller 81 of theadditional casing A 30 via the control line 48 to increase therotational speed of the cooling fan 66. The power controller 81, whenreceiving the signal, increase the rotational speed of the cooling fan66 (S1201). Further, the rotational speed of the cooling fan 66 at thisstage may be previously increased to a level necessary for dissipationof heat to be generated when the disk drive 51β specified by theoperator is put eventually in the “ready” mode. Thereby, the operationof the disk drive 51β is shifted to the “ready” mode faster than theincrease of the rotational speed of the cooling fan 66, thus preventingthe temperature increase within the casing. Also the rotational speed ofthe cooling fan 66 may be gradually increased depending on the risingcondition of the disk drives 51β specified by the operator. When it isdesired to adjust not the rotational speed but the number of drivencooling fans 66, it is also possible to gradually increase the number ofcooling fan 66 to be driven according to the rising condition of thedisk drive 510. In this way, since the cooling fans 66 can be driven ina condition sufficient in the then circumstances, power saving and noisereduction can be realized more effectively.

The disk controller unit 120 then transmits a command to the powercontroller 81 via the control line 48 to instruct the power controller81 to start power supply to the disk drive 51β specified by theoperator. The power controller 81, when receiving the command, controlsthe AC/DC power supply 57 to start the power supply to the disk drive51β specified by the operator (S1202). As result, the disk drive 51β isshifted from the “not ready” mode to the “ready” mode.

The disk controller unit 120 is monitoring the operational state of thedisk drive 51β by inquiry (e.g., by polling) via the control line 48.And as soon as the disk controller unit 120 recognizes the fact that thedisk drive 51β was put in such a condition as able to read or writedata, the disk controller unit starts operation of causing the datastored in the disk drive 51α specified by the operator to be stored inthe associated disk drive 51β (S1203). When the disk controller unit 120recognize the end of the above operation, the disk controller unittransmits a command to the disk drive 51β via the control line 48 toshift the disk drive 51β from the “ready” mode to the “power off” mode(S1204). As a result, the disk drive 51β is put in the “power off” mode(S1205).

The disk controller unit 120 is monitoring the operational state of thedisk drive 51β by the inquiry via the control line 48. And whenrecognizing the fact that the disk drive 51β was shifted to the “poweroff” mode, the disk controller unit 120 transmits a command to the powercontroller 81 of the additional casing 30 via the control line 48 todecrease the rotational speed of the cooling fan 66 of the cooling fanunit 58 mounted in the additional casing 30 (S1206). When receiving thecommand, the power controller 81 reduces the rotational speed of thecooling fan 66, for example, by decreasing a drive voltage for thecooling fan 66 (S1207) and terminates its backup operation.

In this connection, such control can also be realized, for example, bythe disk drive 51β which transmits a command to the cooling fan unit 58to reduce its rotational speed, and the control itself can be carriedout by the CPU mounted in the cooling fan unit 58. The degree ofreduction of the rotational speed of the cooling fan 66 may bedetermined to have a sufficient cooling capacity depending on theoperational mode of the disk drive 51β. Further, the number of drivencooling fans 66 may be adjusted by the power controller 81 whichcontrols the AC/DC power supply 57 depending on the operational state ofthe disk drive 51.

Furthermore, the rotational speed of the cooling fan 66 can also becontrolled finely depending on the operational state of the disk drive51β varying from time to time, by the disk controller unit 120 or by thepower controller 81 of the additional casing 30 which monitors theoperational states of the disk drives 51β in real time or in shortintervals. It is also possible to automatically set the rotational speedat an optimum value based on a temperature detected by a sensor or thelike.

As has been explained above, since the operation of the disk drive 51and the cooling ability of the cooling fan 66 can be controlled at anecessary time such as backup, power saving and noise reduction can berealized.

Although the explanation has been made in connection with the presentembodiment, the embodiment is given only for easy understanding of thepresent invention and thus the present invention is not limited to thespecific example. The present invention can be modified and changedwithout departing from the subject matter of the invention, andobviously, numerous equivalents thereof are included in the presentinvention.

5. Another Embodiment

Various functions of the disk controller unit 120 and power controller81 as mentioned above are not always required to be provided in such amanner as mentioned above. Thus provision of the various functions tothe disk controller unit 120 or power controller 81 can be freelydetermined depending on various circumstances.

The cooling device mounted in the basic casing 20 or additional casing30 is not limited to the aforementioned cooling fan unit 58, but may be,for example, a water-cooling type cooler or a Peltier (effect) element.

In another embodiment, the function of the host computer 300 formeasuring an access frequency to each disk drive 51 may be provided tothe disk array apparatus 10 so that, when the disk array apparatus 10judges that the access frequency to the disk drive 51 (such as SATAdrive) usually operating in the “power off” mode exceeded apredetermined threshold value, data stored in the associated disk drive51 is stored in the disk drive (e.g., FC drive) 51 usually operating inthe “ready” mode. As a result, the lives of the drives can be averagedand thus its maintenance efficiency can be increased.

The present invention can also be applied to a storage apparatus otherthan the disk array apparatus, for example, even to not disk drives butstorage devices using semiconductor disks as storage devices.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A disk array apparatus comprising: a controller, in a casing of aplurality of casings, being adapted to transmit data received from atleast one of a plurality of computers to at least one of a plurality ofstorage areas via an interface other than a Serial ATA (SATA) interface;a plurality of first disk drive units each comprising a converter and afirst type disk drive, the converter converting a communication with theinterface other than the SATA interface into a communication with a SATAinterface, the first type disk drive having the SATA interface and atleast one of the plurality of storage areas; and another casing of theplurality of casings being capable of comprising either the plurality offirst disk drive units or a plurality of second disk drive units, eachof the plurality of second disk drive units comprising a second typedisk drive having the interface other than the SATA interface, whereinthe controller is adapted to acquire information of at least one diskdrive in at least one disk drive unit comprised in the another casing sothat a software program on at least one of the plurality of computerscan cause to display the type of interface of the at least one diskdrive in the at least one disk drive unit comprised in the anothercasing.
 2. The disk array apparatus according to claim 1, wherein: ifthe at least one disk drive unit comprised in the another casing is atleast one of the plurality of first disk drive units, the type ofinterface displayed corresponds to the SATA interface, and if the atleast one disk drive unit comprised in the another casing is at leastone of the plurality of second disk drive units, the type of interfacedisplayed corresponds to the interface other than the SATA interface. 3.The disk array apparatus according to claim 1, further comprising: atransmission line, coupled to the controller, being adapted forcommunication from the controller to the at least one disk drive in theat least one disk drive unit comprised in the another casing via theinterface other than the SATA interface.
 4. The disk array apparatusaccording to claim 1, wherein the controller is adapted to acquireinformation of a plurality of disk drive units comprised in the anothercasing so that the software program can cause to display the type ofinterface of each of a plurality of disk drives of the plurality of diskdrive units comprised in the another casing.
 5. The disk array apparatusaccording to claim 1, wherein the interface other than the SATAinterface is a Fibre Channel (FC) interface.
 6. The disk array apparatusaccording to claim 1, wherein the controller is adapted to acquire theinformation from the at least one disk drive in the at least one diskdrive unit comprised in the another casing.
 7. The disk array apparatusaccording to claim 1, wherein the controller comprises a cache memoryfor temporarily storing data.
 8. The disk array apparatus according toclaim 1, wherein the controller is adapted to store managementinformation including an identifier of the another casing, an identifierof the at least one disk drive in the at least one disk drive unitcomprised in the another casing, and information corresponding to thetype of interface of the at least one disk drive in the at least onedisk drive unit comprised in the another casing.
 9. The disk arrayapparatus according to claim 1, wherein the controller is adapted totransmit the information of the at least one disk drive in the at leastone disk drive unit comprised in the another casing to the softwareprogram.
 10. The disk array apparatus according to claim 1, wherein thecontroller is adapted to control a plurality of disk drives of aplurality of disk drive units comprised in the another casing to storedata according to Redundant Array of Inexpensive Disks (RAID).
 11. Adisk array apparatus comprising: a casing comprising a controller, thecontroller being adapted to execute an operation of writing data,received from at least one of a plurality of computers, to at least oneof a plurality of disk drives accommodated in a plurality of disk driveunits accommodated in another casing via a first type communicationinterface; and the another casing is capable of accommodating either aplurality of first disk drive units or a plurality of second disk driveunits, each of the plurality of first disk drive units comprising aconverter and a first type disk drive, the converter converting acommunication with the first type communication interface into acommunication with a second type communication interface, the first typedisk drive having the second type communication interface, each of theplurality of second disk drive units comprising a second type disk drivehaving the first type communication interface, wherein the controller isadapted to acquire information of the type of communication interface ofat least one disk drive accommodated in at least one of the plurality ofdisk drive units accommodated in the another casing, so that a softwareprogram on at least one of the plurality of computers can cause todisplay the type of communication interface of the at least one diskdrive accommodated in the at least one of the plurality of disk driveunits accommodated in the another casing.
 12. The disk array apparatusaccording to claim 11, wherein: if the at least one of the plurality ofdisk drive units accommodated in the another casing is at least one ofthe plurality of first disk drive units, the type of communicationinterface displayed corresponds to the second type communicationinterface, and if the at least one of the plurality of disk drive unitsaccommodated in the another casing is at least one of the plurality ofsecond disk drive units, the type of communication interface displayedcorresponds to the first type communication interface.
 13. The diskarray apparatus according to claim 11, further comprising: atransmission line, coupled to the controller, being adapted forcommunication from said controller to the plurality of disk drivesaccommodated in a plurality of disk drive units accommodated in theanother casing via the first type communication interface.
 14. The diskarray apparatus according to claim 11, wherein the controller is adaptedto acquire information of the plurality of disk drives accommodated in aplurality of disk drive units accommodated in the another casing so thatthe software program can cause to display the type of communicationinterface of each of the plurality of disk drives accommodated in aplurality of disk drive units accommodated in the another casing. 15.The disk array apparatus according to claim 11, wherein the first typecommunication interface is an interface other than a Serial ATA (SATA)interface.
 16. The disk array apparatus according to claim 11, whereinthe first type communication interface is a Fibre Channel (FC)interface.
 17. The disk array apparatus according to claim 11, whereinthe second type communication interface is a Serial ATA (SATA)interface.
 18. The disk array apparatus according to claim 11, whereinthe controller is adapted to acquire the information from the at leastone disk drive accommodated in the at least one of the plurality of diskdrive units accommodated in the another casing.
 19. The disk arrayapparatus according to claim 11, wherein the controller comprises acache memory for temporarily storing data.
 20. The disk array apparatusaccording to claim 11, wherein the controller is adapted to storemanagement information including an identifier of the another casing, anidentifier of the at least one disk drive accommodated in the at leastone of the plurality of disk drive units accommodated in the anothercasing, and information corresponding to the type of communicationinterface of the at least one disk drive accommodated in the at leastone of the plurality of disk drive units accommodated in the anothercasing.
 21. The disk array apparatus according to claim 11, wherein thecontroller is adapted to transmit the information of the at least onedisk drive accommodated in the at least one of the plurality of diskdrive units accommodated in the another casing to the software program.22. The disk array apparatus according to claim 11, wherein thecontroller is adapted to control the plurality of disk drivesaccommodated in the plurality of disk drive units accommodated in theanother casing to store data according to Redundant Array of InexpensiveDisks (RAID).
 23. A control method of a disk array apparatus comprisingthe steps of: acquiring information of at least one disk drive in atleast one disk drive unit comprised in a casing so that a softwareprogram on at least one of a plurality of computers can cause to displaythe type of interface of the at least one disk drive in the at least onedisk drive unit comprised in the casing; and transmitting, by acontroller in another casing, data received from at least one of aplurality of computers to the at least one disk drive in the at leastone disk drive unit comprised in the casing via an interface other thana Serial ATA (SATA) interface, wherein the casing is capable ofcomprising either a plurality of first disk drive units or a pluralityof second disk drive units, the plurality of first disk drive units eachcomprising a converter and a first type disk drive, the converterconverting a communication with the interface other than the SATAinterface into a communication with the SATA interface, the first typedisk drive having the SATA interface, each of the plurality of seconddisk drive units comprising a second type disk drive having theinterface other than the SATA interface.
 24. The control methodaccording to claim 23, wherein: if the at least one disk drive unitcomprised in the casing is at least one of the plurality of first diskdrive units, the type of interface displayed corresponds to the SATAinterface, and if the at least one disk drive unit comprised in thecasing is at least one of the plurality of second disk drive units, thetype of interface displayed corresponds to the interface other than theSATA interface.
 25. The control method according to claim 23, wherein atransmission line is coupled to the controller and is adapted forcommunication from the controller to the at least one disk drive in theat least one disk drive unit comprised in the casing via the interfaceother than the SATA interface.
 26. The control method according to claim23, wherein the acquiring step includes a step for acquiring informationof a plurality of disk drive units comprised in the casing, so that thesoftware program can cause to display the type of interface of each of aplurality of disk drives of the plurality of disk drive units comprisedin the casing.
 27. The control method according to claim 23, wherein theinterface other than the SATA interface is a Fibre Channel (FC)interface.
 28. The control method according to claim 23, wherein theacquiring step includes a step for acquiring the information from the atleast one disk drive in the at least one disk drive unit comprised inthe casing.
 29. The control method according to claim 23, wherein thecontroller comprises a cache memory for temporarily storing data. 30.The control method according to claim 23, further comprising the stepof: storing, by the controller, management information including anidentifier of the casing, an identifier of the at least one disk drivein the at least one disk drive unit comprised in the casing, andinformation corresponding to the type of interface of the at least onedisk drive in the at least one disk drive unit comprised in the casing.31. The control method according to claim 23, further comprising thestep of: transmitting, by the controller, the information of the atleast one disk drive in the at least one disk drive unit comprised inthe casing to the software program.
 32. The control method according toclaim 23, further comprising the step of: controlling, by thecontroller, a plurality of disk drives of a plurality of disk driveunits comprised in the casing to store data according to Redundant Arrayof Inexpensive Disks (RAID).
 33. A control method for a disk arrayapparatus comprising the steps of: acquiring information of the type ofcommunication interface of at least one disk drive accommodated in atleast one of the plurality of disk drive units accommodated in a casing,so that a software program on at least one of a plurality of computerscan cause to display the type of communication interface of the at leastone disk drive accommodated in the at least one of the plurality of diskdrive units accommodated in the casing; and executing, by a controllerin another casing, an operation of writing data, received from at leastone of the plurality of computers, to the at least one disk driveaccommodated in the at least one of the plurality of disk drive unitsaccommodated in the casing via a first type communication interface,wherein the casing is capable of accommodating either a plurality offirst disk drive units or a plurality of second disk drive units, eachof the plurality of first disk drive units comprising a converter and afirst type disk drive, the converter converting a communication with thefirst type communication interface into a communication with a secondtype communication interface, the first type disk drive having thesecond type communication interface, each of the plurality of seconddisk drive units comprising a second type disk drive having the firsttype communication interface.
 34. The control method according to claim33, wherein: if the at least one of the plurality of disk drive unitsaccommodated in the casing is at least one of the plurality of firstdisk drive units, the type of communication interface displayedcorresponds to the second type communication interface, and if the atleast one of the plurality of disk drive units accommodated in thecasing is at least one of the plurality of second disk drive units, thetype of communication interface displayed corresponds to the first typecommunication interface.
 35. The control method according to claim 33,wherein a transmission line is coupled to the controller and is adaptedfor communication from said controller to the plurality of disk drivesaccommodated in a plurality of disk drive units accommodated in thecasing via the first type communication interface.
 36. The controlmethod according to claim 33, wherein the acquiring step includes a stepfor acquiring information of the plurality of disk drives accommodatedin a plurality of disk drive units accommodated in the casing so thatthe software program can cause to display the type of communicationinterface of each of the plurality of disk drives accommodated in aplurality of disk drive units accommodated in the casing.
 37. Thecontrol method according to claim 33, wherein the first typecommunication interface is an interface other than a Serial ATA (SATA)interface.
 38. The control method according to claim 33, wherein thefirst type communication interface is a Fibre Channel (FC) interface.39. The control method according to claim 33, wherein the second typecommunication interface is a Serial ATA (SATA) interface.
 40. Thecontrol method according to claim 33, wherein the acquiring stepincludes a step for acquiring the information from the at least one diskdrive accommodated in the at least one of the plurality of disk driveunits accommodated in the casing.
 41. The control method according toclaim 33, wherein the controller comprises a cache memory fortemporarily storing data.
 42. The control method according to claim 33,further comprising the step of: storing, by the controller, managementinformation including an identifier of the casing, an identifier of theat least one disk drive accommodated in the at least one of theplurality of disk drive units accommodated in the casing, andinformation corresponding to the type of communication interface of theat least one disk drive accommodated in the at least one of theplurality of disk drive units accommodated in the casing.
 43. Thecontrol method according to claim 33, further comprising the step of:transmitting, by the controller, the information of the at least onedisk drive accommodated in the at least one of the plurality of diskdrive units accommodated in the casing to the software program.
 44. Thecontrol method according to claim 33, further comprising the step of:controlling, by the controller, the plurality of disk drivesaccommodated in the plurality of disk drive units accommodated in thecasing to store data according to Redundant Array of Inexpensive Disks(RAID).
 45. A disk array apparatus comprising: a casing is capable ofcomprising either a plurality of first disk drive units or a pluralityof second disk drive units, the plurality of first disk drive units eachcomprising a converter and a first type disk drive, the converterconverting a communication with an interface other than a Serial ATA(SATA) interface into a communication with the SATA interface, the firsttype disk drive having the SATA interface, each of the plurality ofsecond disk drive units comprising a second type disk drive having aninterface other than the SATA interface; another casing comprising acontroller, the controller transmitting data received from at least oneof a plurality of computers to at least one disk drive in at least onedisk drive unit comprised in the casing via the communication with theinterface other than the SATA interface; and the controller beingadapted to acquire information of the at least one disk drive in the atleast one disk drive unit comprised in the casing so that a softwareprogram on at least one of the plurality of computers can cause todisplay the type of interface of the at least one disk drive in the atleast one disk drive unit comprised in the casing.
 46. The disk arrayapparatus according to claim 45, wherein: if the at least one disk driveunit comprised in the casing is at least one of the plurality of firstdisk drive units, the type of interface displayed corresponds to theSATA interface, and if the at least one disk drive unit comprised in thecasing is at least one of the plurality of second disk drive units, thetype of interface displayed corresponds to the interface other than theSATA interface.
 47. The disk array apparatus according to claim 45,further comprising: a transmission line, coupled to the controller,being adapted for communication from the controller to the at least onedisk drive in the at least one disk drive unit comprised in the casingby the communication with the interface other than the SATA interface.48. The disk array apparatus according to claim 45, wherein thecontroller is adapted to acquire information of a plurality of diskdrive units comprised in the casing, so that the software program cancause to display the type of interface of each of a plurality of diskdrives of the plurality of disk drive units comprised in the casing. 49.The disk array apparatus according to claim 45, wherein the interfaceother than the SATA interface is a Fibre Channel (FC) interface.
 50. Thedisk array apparatus according to claim 45, wherein the controller isadapted to acquire the information from the at least one disk drive inthe at least one disk drive unit comprised in the casing.
 51. The diskarray apparatus according to claim 45, wherein the controller comprisesa cache memory for temporarily storing data.
 52. The disk arrayapparatus according to claim 45, wherein the controller is adapted tostore management information including an identifier of the casing, anidentifier of the at least one disk drive in the at least one disk driveunit comprised in the casing, and information corresponding to the typeof interface of the at least one disk drive in the at least one diskdrive unit comprised in the casing.
 53. The disk array apparatusaccording to claim 45, wherein the controller is adapted to transmit theinformation of the at least one disk drive in the at least one diskdrive unit comprised in the casing to the software program.
 54. The diskarray apparatus according to claim 45, wherein the controller isarranged to control a plurality of disk drives of a plurality of diskdrive units comprised in the casing to store data according to RedundantArray of Inexpensive Disks (RAID).